Enviro-Tablets&trade; AquaCare&trade; 500 Pond and Aquarium Water Maintenance Cleans and clarifies water in Aquariums and Ponds up to 500 gallons. Safe for domestic Koi and fish ponds, commercial lakes and commercial shellfish ponds. Removes and eliminates Odors and organic sludge by boosting filter bacteria colonies. Eliminates Algae and Blanket Weed. Saves Money and Time-Reduces manual cleaning time, requires less Aeration and cleans the entire filter system of the pond. Good for MULTIPLE MONTHS of Treatment! Aids Fish Health-Probiotic activity prevents parasite establishment, increases dissolved oxygen and neutralizes ammonia. Environmentally Friendly, Non-Hazardous and safe for domestic Koi and fish. 100% All Natural - Completely Safe to Handle!